From: ES <ruby-ml@...>
Date: 2005-10-14T11:12:06+09:00
Subject: Re: instance from class name?

David A. Black wrote:
> Hi --
> 
> On Fri, 14 Oct 2005, ES wrote:
> 
>> David A. Black wrote:
>>
>>> Hi --
>>>
>>> On Thu, 13 Oct 2005, Alexander Lamb wrote:
>>>
>>>> Hello,
>>>>
>>>> I am new to this list (and language) but I didn't find my answer 
>>>> from the documentation available.
>>>>
>>>> I simply would like to do something like:
>>>>
>>>> myObject = class.fromName("a_class_name").new
>>
>>
>> Classes are stored as constants in ruby. Witness Mr. Black's solution:
>>
>>> my_object = Object.const_get("MyClass").new
>>>
>>> or some variation of that.
>>
>>
>> That works; however, if your class name looks like SomeModule::SomeClass,
>> you will need to be a bit fancier because const_get only looks for 
>> constants
>> in the current class or module (the top-level Object instance is the 
>> default):
>>
>>  class_name.split('::').inject(Object) {|parent, obj| parent.const_get 
>> obj}.new
> 
> 
> Like Kernel#singleton_class, this is one of those things that gets
> written again and again, ad hoc.  I wonder if it might be a candidate
> for a permanent modification to const_get....

If only :) Although I think that it might be more appropriate to have
something like ObjectSpace.const_get for that use.

> David

E